This invention relates to the field of conducting organic polymers and particularly to polypyrrole polymers.
Within the last few years, polymers have been discovered which have metallic properties, particularly high electrical conductivity. These polymers include polysulfur nitride, (SN).sub.x, doped polyacetylene, (CH).sub.x, and polypyrrole.
Although there are many potential applications for conducting polymers, their use has been thwarted by the fact that they are chemically unstable, have poor mechanical properties, and/or are difficult to produce in suitable forms.
Polypyrrole which is chemically more stable than the polysulfur nitride or the doped polyacetylene has proven to be very brittle. Thin polypyrrole films (from about 20 nm to 20 .mu.m thick) have been produced on electrodes by electropolymerization. These films have been proposed for use as electrode surfaces. However these prior art films are too thin and too brittle to be useful in most structural-related applications.
Polypyrrole is produced by electropolymerization as described by A. F. Diaz, et al in an article entitled "Electrochemical Polymerization of Pyrrole" in the Journal of Chemical Society, Chemical Communications, 1979, page 635. This process produces very thin (from about 20 nm to 20 .mu.m) durable films. N-substituted analogs of pyrrole such as poly-N-methylpyrrole and poly-N-phenylpyrrole have been used to form polypyrrole as reported by A. F. Diaz, et al in an article entitled "Electrochemistry of Conducting Polypyrrole Films" in the Journal of Electroanalytical Chemistry, 129, (1981) pages 115-132. In these processes, small anions such as tetrafluoroborate, bisulfate, and perchlorate from the electrolyte are used to dope the polymer and balance its cationic charge. However, these small anions do not provide the resultant polymer with the bulk and ductility needed to make the material useful in structural-related applications.